diff --git a/src/jtag/drivers/cmsis_dap.c b/src/jtag/drivers/cmsis_dap.c
index 5e01d0647..364a17746 100644
--- a/src/jtag/drivers/cmsis_dap.c
+++ b/src/jtag/drivers/cmsis_dap.c
@@ -229,7 +229,7 @@ static int pending_scan_result_count;
 static struct pending_scan_result pending_scan_results[MAX_PENDING_SCAN_RESULTS];
 
 /* queued JTAG sequences that will be executed on the next flush */
-#define QUEUED_SEQ_BUF_LEN (cmsis_dap_handle->packet_size - 3)
+#define QUEUED_SEQ_BUF_LEN (cmsis_dap_handle->packet_usable_size - 3)
 static int queued_seq_count;
 static int queued_seq_buf_end;
 static int queued_seq_tdo_ptr;
diff --git a/src/jtag/drivers/cmsis_dap.h b/src/jtag/drivers/cmsis_dap.h
index 80044199b..72e07fb04 100644
--- a/src/jtag/drivers/cmsis_dap.h
+++ b/src/jtag/drivers/cmsis_dap.h
@@ -27,6 +27,7 @@ struct cmsis_dap {
 	struct cmsis_dap_backend_data *bdata;
 	const struct cmsis_dap_backend *backend;
 	unsigned int packet_size;
+	unsigned int packet_usable_size;
 	unsigned int packet_buffer_size;
 	uint8_t *packet_buffer;
 	uint8_t *command;
diff --git a/src/jtag/drivers/cmsis_dap_usb_bulk.c b/src/jtag/drivers/cmsis_dap_usb_bulk.c
index 55b9a558a..6599c414c 100644
--- a/src/jtag/drivers/cmsis_dap_usb_bulk.c
+++ b/src/jtag/drivers/cmsis_dap_usb_bulk.c
@@ -352,25 +352,17 @@ static int cmsis_dap_usb_open(struct cmsis_dap *dap, uint16_t vids[], uint16_t p
 				return ERROR_FAIL;
 			}
 
-			dap->packet_size = packet_size;
-			dap->packet_buffer_size = packet_size;
 			dap->bdata->usb_ctx = ctx;
 			dap->bdata->dev_handle = dev_handle;
 			dap->bdata->ep_out = ep_out;
 			dap->bdata->ep_in = ep_in;
 			dap->bdata->interface = interface_num;
 
-			dap->packet_buffer = malloc(dap->packet_buffer_size);
-			if (!dap->packet_buffer) {
-				LOG_ERROR("unable to allocate memory");
+			err = cmsis_dap_usb_alloc(dap, packet_size);
+			if (err != ERROR_OK)
 				cmsis_dap_usb_close(dap);
-				return ERROR_FAIL;
-			}
 
-			dap->command = dap->packet_buffer;
-			dap->response = dap->packet_buffer;
-
-			return ERROR_OK;
+			return err;
 		}
 
 		libusb_close(dev_handle);
@@ -445,6 +437,8 @@ static int cmsis_dap_usb_alloc(struct cmsis_dap *dap, unsigned int pkt_sz)
 	dap->packet_buffer = buf;
 	dap->packet_size = pkt_sz;
 	dap->packet_buffer_size = pkt_sz;
+	/* Prevent sending zero size USB packets */
+	dap->packet_usable_size = pkt_sz - 1;
 
 	dap->command = dap->packet_buffer;
 	dap->response = dap->packet_buffer;
diff --git a/src/jtag/drivers/cmsis_dap_usb_hid.c b/src/jtag/drivers/cmsis_dap_usb_hid.c
index 592eb0925..52dfd7616 100644
--- a/src/jtag/drivers/cmsis_dap_usb_hid.c
+++ b/src/jtag/drivers/cmsis_dap_usb_hid.c
@@ -213,6 +213,7 @@ static int cmsis_dap_hid_alloc(struct cmsis_dap *dap, unsigned int pkt_sz)
 
 	dap->packet_buffer = buf;
 	dap->packet_size = pkt_sz;
+	dap->packet_usable_size = pkt_sz;
 	dap->packet_buffer_size = packet_buffer_size;
 
 	dap->command = dap->packet_buffer + REPORT_ID_SIZE;